Progression instance that behaves like a range of integers, from 0 to the given
ending value, exclusive.Progressions API.Progression instance with the given starting, ending, and stepping
values.Progression outside of this library.Progression instance that behaves like a range of integers, with the given
starting and ending values.Progression instance that behaves like a range of all valid indices
of the given array.Progression instance whose starting value is this progression's ending value,
and vice versa.Integer array filled with all the integers in this progression, in iteration order.